internal override RayHitTestParameters RayFromViewportPoint(Point p, Size viewSize, Rect3D boundingRect, out double distanceAdjustment) { // The camera may be animating. Take a snapshot of the current value // and get the property values we need. (Window OS #992662) Point3D position = Position; Vector3D lookDirection = LookDirection; Vector3D upDirection = UpDirection; double zn = NearPlaneDistance; double zf = FarPlaneDistance; double width = Width; // // Compute rayParameters // // Find the point on the projection plane in post-projective space where // the viewport maps to a 2x2 square from (-1,1)-(1,-1). Point np = M3DUtil.GetNormalizedPoint(p, viewSize); double aspectRatio = M3DUtil.GetAspectRatio(viewSize); double w = width; double h = w / aspectRatio; // Direction is always perpendicular to the viewing surface. Vector3D direction = new Vector3D(0, 0, -1); // Apply the inverse of the view matrix to our ray. Matrix3D viewMatrix = CreateViewMatrix(Transform, ref position, ref lookDirection, ref upDirection); Matrix3D invView = viewMatrix; invView.Invert(); // We construct our ray such that the origin resides on the near // plane. If our near plane is too far from our the bounding box // of our scene then the results will be inaccurate. (e.g., // OrthographicCameras permit negative near planes, so the near // plane could be at -Inf.) // // However, it is permissable to move the near plane nearer to // the scene bounds without changing what the ray intersects. // If the near plane is sufficiently far from the scene bounds // we make this adjustment below to increase precision. Rect3D transformedBoundingBox = M3DUtil.ComputeTransformedAxisAlignedBoundingBox( ref boundingRect, ref viewMatrix); // DANGER: The NearPlaneDistance property is specified as a // distance from the camera position along the // LookDirection with (Near < Far). // // However, when we transform our scene bounds so that // the camera is aligned with the negative Z-axis the // relationship inverts (Near > Far) as illustrated // below: // // NearPlane Y FarPlane // | ^ | // | | | // | | (rect.Z + rect.SizeZ) | // | | o____ | // | | | | | // | | | | | // | | ____o | // | | (rect.Z) | // | Camera -> | // +Z <----------+----------------------------> -Z // | 0 | // // It is surprising, but its the "far" side of the // transformed scene bounds that determines the near // plane distance. double zn2 = -AddEpsilon(transformedBoundingBox.Z + transformedBoundingBox.SizeZ); if (zn2 > zn) { // // Our near plane is far from our children. Construct a new // near plane that's closer. Note that this will modify our // distance computations, so we have to be sure to adjust our // distances appropriately. // distanceAdjustment = zn2 - zn; zn = zn2; } else { // // Our near plane is either close to or in front of our // children, so let's keep it -- no distance adjustment needed. // distanceAdjustment = 0.0; } // Our origin is the point normalized to the front of our viewing volume. // To find our origin's x/y we just need to scale the normalize point by our // width/height. In camera space we are looking down the negative Z axis // so we just set Z to be -zn which puts us on the projection plane // (Windows OS #1005064). Point3D origin = new Point3D(np.X * (w / 2), np.Y * (h / 2), -zn); invView.MultiplyPoint(ref origin); invView.MultiplyVector(ref direction); RayHitTestParameters rayParameters = new RayHitTestParameters(origin, direction); // // Compute HitTestProjectionMatrix // Matrix3D projectionMatrix = GetProjectionMatrix(aspectRatio, zn, zf); // The projectionMatrix takes camera-space 3D points into normalized clip // space. // The viewportMatrix will take normalized clip space into // viewport coordinates, with an additional 2D translation // to put the ray at the origin. Matrix3D viewportMatrix = new Matrix3D(); viewportMatrix.TranslatePrepend(new Vector3D(-p.X, viewSize.Height - p.Y, 0)); viewportMatrix.ScalePrepend(new Vector3D(viewSize.Width / 2, -viewSize.Height / 2, 1)); viewportMatrix.TranslatePrepend(new Vector3D(1, 1, 0)); // `First world-to-camera, then camera's projection, then normalized clip space to viewport. rayParameters.HitTestProjectionMatrix = viewMatrix * projectionMatrix * viewportMatrix; return(rayParameters); }
/// <summary> /// Transforms the bounding box to the smallest axis aligned bounding box /// that contains all the points in the original bounding box /// </summary> /// <param name="rect">Bounding box</param> /// <returns>The transformed bounding box</returns> public override Rect3D TransformBounds(Rect3D rect) { return(M3DUtil.ComputeTransformedAxisAlignedBoundingBox(ref rect, this)); }
/// <summary> /// Returns the bounds of the Model3D subgraph rooted at this Model3D. /// /// Outer space refers to the space after this Model's Transform is /// applied -- or said another way, applying a transform to this Model /// affects it's outer bounds. (While its inner bounds remain unchanged.) /// </summary> internal Rect3D CalculateSubgraphBoundsOuterSpace() { Rect3D innerBounds = CalculateSubgraphBoundsInnerSpace(); return(M3DUtil.ComputeTransformedAxisAlignedBoundingBox(ref innerBounds, Transform)); }